Prevention and management of diabetic retinopathy in STZ diabetic rats by Tinospora cordifolia and its molecular mechanisms

We investigated the potential of Tinospora cordifolia (TC) in treatment of diabetic retinopathy in STZ-induced rats due to its antihyperglycemic, angiogenic, antiinflammatory and antioxidant effects. The diabetic rats, treated for 24 weeks with TC extract (250 mg/kg), were evaluated for lenticular and fundus changes. Biochemical parameters were estimated and histopathological studies performed. TC significantly reduced blood glucose and glycated hemoglobin in treated rats. It prevented cataract development in treated group. Angiogenic markers VEGF and PKC increased in diabetic retina, which reduced significantly with TC. Anti-inflammatory parameters TNF-α and IL-1β elevated in diabetic group unlike that in treated group. TC also provided defense against depletion of antioxidant enzymes- glutathione and catalase. Histopathological studies revealed thickening of basement membrane of the retinal and glomerular vasculature of diabetic rat, but no basement membrane widening was seen in treated animals. Destruction of pancreatic islet structure was observed in diabetic group, but not in treated. Thus, TC reduces blood glucose and inhibits overexpression of angiogenic and inflammatory mediators, which are distinct markers of diabetic retinopathy. It also prevents retinal oxidative stress and restores antioxidant enzyme levels. These data provide evidence for the safety and potential effect of TC in the management of experimental diabetic retinopathy.